1. Field of the Invention
The present invention relates generally to a camera module having a focusing function, and in particular, to a method for measuring a distance using a camera module, capable of measuring a distance between a desired object and a user only through an operation of focusing on the desired object.
2. Description of the Related Art
A variety of methods for measuring a distance between a desired object and a user have been previously provided. For example, the methods include methods for measuring a close distance of several meters between an object and a user, and methods for measuring a long distance ranging from several hundred meters to several kilometers between an object and a user.
The methods for measuring the close distance use ultrasonic waves. The methods using the ultrasonic waves transmit ultrasonic waves to an object, sense the waves reflected by the object, and measure a distance up to the object using a time consumed until the waves come back and speed of the waves. For example, a device using such ultrasonic waves is installed in a rear bumper of a vehicle and provides a distance, from the vehicle to an obstacle, to a driver in real-time when the vehicle is in reverse, thereby preventing an unexpected accident in advance. Also, a laser device is used to measure a relatively long distance. The laser device also emits a laser beam onto an object to be measured using a predetermined laser generator, and measures a distance up to the object using a time consumed when the beam is reflected by the object and comes back, and speed of the laser beam. The laser device can also be used in a construction spot or for military purposes.
In a conventional art, a device for performing distance measurement is provided independently or provided additionally to a predetermined device. For example, a portable terminal having the above-described device for measuring a distance often appears. That is, the portable terminal has an ultrasonic wave or laser beam generator as a light-emitting unit, and a light-receiving unit for receiving ultrasonic waves, a laser beam, and so forth reflected by an object. Therefore, a user can measure a distance between a desired object and a user.
However, when the above-described device for measuring a distance is additionally provided to other apparatus, the device should be separately provided, which generates space limitation. Even when a space is secured, a whole volume of an apparatus increases, which is contradictory to a recent miniaturization trend, and additional manufacturing costs are generated.